1. Field of the Invention
The present invention relates to a device used to couple prosthetic components, and more particularly to adjustably couple prosthetic components in a selected angular relationship.
2. Description of the Related Art
Sometimes, due to accidents, health problems, birth defects, etc., people 5 need to have a limb 6 amputated. The amputated limb 6 terminates in a stump 7. In general, a socket 10 can be formed for a particular stump 7. Those sockets 10 are well known in the art, and each socket 10 has a central axis 11.
Fortunately for people requiring a prosthetic limb, much advancement has been made in the field of prosthetic limbs. Patients now have many choices, including endoskeletal and exoskeletal prosthetic limbs. The present invention relates to endoskeletal prosthetic limbs. That is, limbs comprised of structural components and an optional aesthetic outer shell.
Many prosthetic components are available for use in endoskeletal prosthetic limbs. One of the most common types of prosthetic components is a pylon, which can comprise an aluminum or titanium alloy tube of predetermined length. A clamp can be used to connect to a pylon. Some connectors have two opposed clamps for coupling two pylons. These types of connectors are effective at coupling pylons in a fixed manner. For example, some connectors of this type couple two pylons in a linear manner, where the two pylons are parallel to each other. Other connectors of this type are angled. For example, Otto Bock manufactures a part, having part number 4R56, that provides a fixed and angled connector for two pylons. There is no internal adjustability provided by these types of connectors. Hence, these connectors are incapable of making angular adjustments between two prosthetic components being coupled without additional components.
Another type of existing prosthetic component is a pyramidal adapter, which is adapted to be received within a receiver that has four screws that clamp onto the sides of the pyramid. Using a pyramidal adapter in combination with a receiver is useful in making angular adjustments in both the lateral-medial directions, 15 and 16 respectively, and anterior-posterior directions, 17 and 18 respectively. Yet, the combination of the pyramidal adapter and receiver is only useful for making angular adjustments within a limited range. This limitation is demonstrated in FIG. 1, where the socket 10 has an end 12 that is not perpendicular to the socket central axis 11. Thus, a three prong adapter 20 that is connected to the end 12 of the socket has a central axis 21 that is not parallel with the socket central axis 11. Rather, the three prong adapter central axis 21 is offset from the socket central axis 11 by an angle α. Angle α can have both a lateral-medial component and an anterior-posterior component. Further, the angle α is greater than the angular adjustability possible by using a pyramidal adapter 30 and receiver 45 combination, which is shown as angle β. It is demonstrated that because angle α is greater that the maximum angular adjustability between the pyramidal adapter 30 and fixed receiver 45, angle β, the pylon longitudinal axis 46 is not parallel to the socket central axis 11. This may seriously interfere with a person's ability to walk. Thus, existing pyramidal adapters 30 and receiver 45 combinations may fail to meet the needs of some people.
This type of pyramidal adapter and receiver combination is further illustrated in U.S. Pat. No. 3,659,294. This patent shows an adjustable link for a prosthetic limb. Two parts are shown. One part has a frustopyramidal male end. The second part is a female socket. The socket connects to the frustopyramidal male end in an angular configuration. The link shown in this patent may work well for its intended purpose. However, as discussed above, there is a limit to the adjustability of the link, which can be smaller than necessary depending on a particular patient's needs. Also, the device shown in this patent has no preset adjustments. Further, the device shown in this patent is not adjustable about a fixed axis of rotation.
U.S. Pat. No. 5,888,232 to Taylor discloses an adjusting connector having a pylon or an adapter with a convexly hemispherical protruding portion. A female contact surface with a concavely hemispherical seat is necessary for use with the convexly hemispherical protruding portion of the adapter and pylon. These components are not interchangeable with existing prosthetic components. Further, these components do not rotate about a fixed axis of rotation.
Thus, there exists a need for an angularly variable coupler that solves these and other problems.